1. Field of the Invention
The present invention relates to a vibration type brushless motor utilized for a vibration generating source of a pager and a portable telephone for which demand is rapidly increasing.
2. Description of the Related Art
FIG. 23 is an exploded view of a vibration type motor of the prior art.
FIG. 24 is a cross sectional view of another vibration type motor of the prior art.
FIG. 25 is a perspective view of a rotor utilized for a vibration type motor of the prior art.
FIG. 26 is a perspective view of another type of rotor utilized for a vibration type motor of the prior art.
The Japanese Patent Application Laid-open Publication No. 7-20063/1995 discloses the vibration type motor shown in FIG. 23. As shown in FIG. 23, an unbalance-weight 9 is inserted into a shaft P3. By the rotation of the shaft P3 mounted with the unbalance-weight 9, vibration is generated.
The Japanese Patent Application Laid-open Publications No. 9-93862/1997 and No. 2000-262969 disclose a vibration type motor shown in FIG. 24. As shown in FIG. 24, an unbalance-weight 9 is mounted on an outer circumference area of a rotor 8. Vibration is generated by rotating the rotor 8 mounted with the unbalance-weight 9. Further, the Japanese Patent Application Laid-open Publication No. 11-341769/1999 also discloses the similar construction to the vibration type motor shown in FIG. 24.
The Japanese Patent Application Laid-open Publications No. 2-17853/1990 and No. 9-294352/1997 disclose a rotor 8 shown in FIGS. 25 and 26 respectively. In FIG. 25, a part of a flat coil 10 is removed from the rotor 8. In FIG. 26, a weight 11 is provided on the rotor 8 instead of a flat coil having been removed. In either case, the rotor 8 generates vibration due to unbalanced rotation of the rotor 8.
Furthermore, the Japanese Patent Application Laid-open Publication No. 2-17853/1990 discloses that vibration caused by unbalanced rotation of a rotor is generated by reducing a number of windings or coil shape of one coil out of three air-core coils. Moreover, the Japanese Patent Application Laid-open Publication No. 9-93862/1997 discloses that vibration is generated by a rotation of rotor of which center of gravity is shifted eccentrically by attaching a deformed metal member having high specific gravity on an outer circumference area of a coreless rotor formed integrally with air-core coils by resin.
As mentioned above, each vibration type motor disclosed by the Japanese Patent Application Laid-open Publication Nos. 7-20063/1995, 9-93862/1997 and 2000-262969 is on the basis of the construction of mounting the unbalance weigh on the shaft. Consequently, a total cost of the vibration type motor increases by the unbalance weigh in addition to the basic part cost of the motor itself. Further, manpower for mounting the unbalance-weight on the shaft also increases. Furthermore, it is hard to miniaturize a motor having such the construction because an extra space for rotating the unbalance-weight is necessary for the motor externally or internally.
In the case of each vibration type motor disclosed by the Japanese Patent Application Laid-open Publication Nos. 2-17853/1990 and 9-294352/1997, its construction is composed of a movable flat coil. However, higher effect of vibration can not be obtained.
In the case of the vibration type motor disclosed by the Japanese Patent Application Laid-open Publication No. 2-17853/1990, mass of the air-core coil itself is too small to obtain enough vibration. In the case of the vibration type motor disclosed by the Japanese Patent Application Laid-open Publication No. 9-93862/1997, there also existed a problem such that the deformed member formed by a metal having high specific gravity is essential.
Accordingly, in consideration of the above-mentioned problems of the prior art, an object of the present invention is to provide a vibration type motor, which can improve vibration effect without increasing cost or manpower for assembling.
In order to achieve the above object, the present invention provides, according to a first aspect thereof, a vibration type brushless motor in a structure of brushless motor having an outer rotor type core comprising: a rotor yoke; a shaft of which one end is held by a bearing member so as to rotate freely and another end is fixed to a center of rotation of the rotor yoke; a magnet in an arc; and a ring core arranged around the shaft, the rotor yoke having a side section being formed in a shape of which a part is cut off radially to the outer circumference direction from the center of rotation of the rotor yoke fixed with the other end of the shaft, wherein the ring magnet is fixed to the side section of the rotor yoke with facing the ring core, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor yoke.
According to a second aspect of the present invention, there provided a vibration type brushless motor in a structure of brushless motor having an outer rotor type core comprising: a rotor yoke; a shaft of which one end is held by a bearing member so as to rotate freely and another end is fixed to a center of rotation of the rotor yoke; a magnet in an arc; and a ring core arranged around the shaft, the rotor yoke having a ceiling section formed in a disc shape with centering the center of rotation of the rotor yoke fixed with the other end of the shaft and a side section connecting with an outer circumference edge of the ceiling section, wherein a part of the side section is cut off in a circular arc, and wherein the ring magnet is fixed to the side section of the rotor yoke with facing the ring core, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor yoke.
According to a third aspect of the present invention, there provided a vibration type brushless motor in a structure of brushless motor having an outer rotor type core comprising: a rotor yoke; a shaft of which one end is held by a bearing member so as to rotate freely and another end is fixed to a center of rotation of the rotor yoke; a magnet in an arc; and a ring core arranged around the shaft, the rotor yoke having a ceiling section formed in a disc shape with centering the center of rotation of the rotor yoke fixed with the other end of the shaft and a side section connecting with an outer circumference edge of the ceiling section, wherein a part of the ceiling section is cut off radially to an outer circumference direction from the center of rotation of the rotor yoke, and wherein the ring magnet is fixed to the side section of the rotor yoke with facing the ring core, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor yoke.
According to a fourth aspect of the present invention, there provided a vibration type brushless motor in a structure of an axial gap type brushless motor comprising: a rotor composed of a rotor yoke having a ceiling section, a magnet fixed to the rotor yoke and a shaft of which one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a plurality of air-core coils arranged in a ring around the bearing member, the magnet in one shape out of a circular arc of which a part is cut off radially to an outer circumference direction from the center of rotation of the rotor yoke and a disc of which a part is cut off a part of the magnet, wherein the ring magnet is arranged to face the plurality of air-core coils, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor.
According to a fifth aspect of the present invention, there provided a vibration type brushless motor in a structure of an axial gap type brushless motor comprising: a rotor composed of a rotor yoke having a ceiling section, a magnet fixed to the rotor yoke and a shaft, wherein one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a plurality of air-core coils arranged in a ring around the bearing member, the magnet in a disc shape having a hollow section in an approximate circle being provided so as to surround the center of rotation, wherein the magnet has a center being shifted from the center of rotation of the rotor yoke and is arranged to face the plurality of air-core coils, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor caused by the shifted center of the hollow section with respect to the center of rotation of the rotor yoke.
According to a sixth aspect of the present invention, there provided a vibration type brushless motor comprising: a rotor composed of a rotor yoke, a ring magnet fixed to the rotor yoke and a shaft, wherein one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a core having a plurality of salient poles arranged in a ring around the bearing member, the ring magnet having an inner hole and facing the core having the plurality of salient poles, wherein a center of the inner hole coincides with the center of rotation of the rotor yoke, and wherein a center of the outer circumference of the ring magnet is shifted from the center of rotation of the rotor yoke by a predetermined shifting distance, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor.
According to a seventh aspect of the present invention, there provided a vibration type brushless motor comprising: a rotor composed of a rotor yoke, a ring magnet fixed to the rotor yoke and a shaft, wherein one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a core having a plurality of salient poles arranged in a ring around the bearing member, the ring magnet having an inner hole and facing the core having the plurality of salient poles, wherein both a center of the inner hole and a center of an outer circumference of the ring magnet coincide with the center of rotation of the rotor yoke within a range of approximately 0 to 180 degrees in the mechanical angle with centering the center of rotation of the rotor yoke, and wherein the center of the inner hole coincides with the center of rotation of the rotor yoke within a range of approximately 180 to 360 degrees in the mechanical angle, and wherein the center of the outer circumference of the ring magnet is shifted from the center of rotation of the rotor yoke by a predetermined shifting distance within a range of approximately 180 to 360 degrees in the mechanical angle, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor.
According to an eighth aspect of the present invention, there provided a vibration type brushless motor comprising: a rotor composed of a rotor yoke, a magnet in disc shape fixed to the rotor yoke and a shaft, wherein one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a plurality of air-core coils arranged in a ring around the bearing member, the magnet having an inner hole, wherein a center of the inner hole coincides with the center of rotation of the rotor yoke, and wherein a center of an outer circumference of the magnet is shifted from the center of rotation of the rotor yoke by a predetermined shifting distance, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor.
According to a ninth aspect of the present invention, there provided a vibration type brushless motor comprising: a rotor composed of a rotor yoke, a magnet in disc shape fixed to the rotor yoke and a shaft, wherein one end of the shaft is fixed to a center of rotation of the rotor yoke and another end of the shaft is held by a bearing member so as to rotate freely; and a plurality of air-core coils arranged in a ring around the bearing member, the ring magnet having an inner hole, wherein both a center of the inner hole and a center of an outer circumference of the ring magnet coincide with the center of rotation of the rotor yoke within a range of approximately 0 to 180 degrees in the mechanical angle with centering the center of rotation of the rotor yoke, and wherein the center of the inner hole coincides with the center of rotation of the rotor yoke within a range of approximately 180 to 360 degrees in the mechanical angle, and wherein the center of the outer circumference of the ring magnet is shifted from the center of rotation of the rotor yoke by a predetermined shifting distance within a range of approximately 180 to 360 degrees in the mechanical angle, the vibration type brushless motor is further characterized in that vibration is generated by unbalanced vibration of the rotor.
Other object and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.